// TIJDELIJKE debug-endpoint voor M8-acceptance.
// Geen auth, geen filtering — alle pg_notify-events op `scrum4me_changes`
// stromen rauw door naar de browser. Bedoeld om te isoleren of de
// SSE + LISTEN-pipe op Vercel werkt, los van iron-session, productfilter
// of solo-store.
//
// VERWIJDEREN VOOR M8 OUT-OF-DRAFT.

import { NextRequest } from 'next/server'
import { Client } from 'pg'

export const runtime = 'nodejs'
export const dynamic = 'force-dynamic'
export const maxDuration = 300

const CHANNEL = 'scrum4me_changes'

export async function GET(request: NextRequest) {
  const directUrl = process.env.DIRECT_URL ?? process.env.DATABASE_URL
  if (!directUrl) {
    return Response.json({ error: 'DIRECT_URL/DATABASE_URL niet gezet' }, { status: 500 })
  }

  const isPooled = directUrl.includes('pooler.')
  const hostHint = directUrl.match(/@([^/]+)/)?.[1] ?? 'unknown-host'
  console.log(`[debug-realtime] connecting (${isPooled ? 'POOLED' : 'direct'}) host=${hostHint}`)

  const encoder = new TextEncoder()
  const pgClient = new Client({ connectionString: directUrl })
  let closed = false
  let heartbeatTimer: ReturnType<typeof setInterval> | null = null

  const stream = new ReadableStream({
    async start(controller) {
      const enqueue = (chunk: string) => {
        if (closed) return
        try {
          controller.enqueue(encoder.encode(chunk))
        } catch {
          // already closed
        }
      }

      const cleanup = async (reason: string) => {
        if (closed) return
        closed = true
        if (heartbeatTimer) clearInterval(heartbeatTimer)
        try {
          await pgClient.end()
        } catch {
          // ignore
        }
        try {
          controller.close()
        } catch {
          // already closed
        }
        console.log(`[debug-realtime] closed: ${reason}`)
      }

      try {
        await pgClient.connect()
        await pgClient.query(`LISTEN ${CHANNEL}`)
        console.log('[debug-realtime] LISTEN ready')
      } catch (err) {
        console.error('[debug-realtime] pg connect/listen failed:', err)
        enqueue(`event: error\ndata: ${JSON.stringify({ message: String(err) })}\n\n`)
        await cleanup('pg connect failed')
        return
      }

      pgClient.on('notification', (msg) => {
        console.log(`[debug-realtime] RAW notification length=${msg.payload?.length ?? 0}`)
        if (!msg.payload) return
        enqueue(`data: ${msg.payload}\n\n`)
      })

      pgClient.on('error', async (err) => {
        console.error('[debug-realtime] pg client error:', err)
        await cleanup('pg error')
      })

      pgClient.on('end', () => {
        console.log('[debug-realtime] pg client end')
      })

      enqueue(
        `event: ready\ndata: ${JSON.stringify({
          host: hostHint,
          pooled: isPooled,
          channel: CHANNEL,
          time: new Date().toISOString(),
        })}\n\n`,
      )

      heartbeatTimer = setInterval(() => {
        enqueue(`: heartbeat ${new Date().toISOString()}\n\n`)
      }, 25_000)

      request.signal.addEventListener('abort', () => {
        cleanup('client aborted')
      })
    },
  })

  return new Response(stream, {
    headers: {
      'Content-Type': 'text/event-stream; charset=utf-8',
      'Cache-Control': 'no-cache, no-transform',
      Connection: 'keep-alive',
      'X-Accel-Buffering': 'no',
    },
  })
}